(ITS#5632) "overlay" directive listing in slapd.conf misleading

Full_Name: Quanah Gibson-Mount
Version: 2.4
OS: NA
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (75.111.29.239)
The "overlay" directive in slapd.conf is listed under "general database
options", but it can in fact be global, depending on the overlay. At least the
wording in slapd.conf for this directive should be updated to reflect that.